A World to Explore

Whitey Hagadorn beginning his GSA talk on the feeding abilities of Anomalocaris. The large room was packed.

DENVER, COLORADO — I very much enjoyed a talk this afternoon by Whitey Hagadorn (a Wooster favorite since his Osgood lecture last year) entitled: “Putting Anomalocaris on a soft-food diet?” Even though Whitey says Anomalocaris “may still have been a fearsome predator”, slurping up worms from the mud is not the same as crunching trilobites. Spaghetti vs. steak.

Whitey’s presentation was an excellent example of testing a hypothesis with fossil evidence. If Anomalocaris really did bite through trilobite cuticle, surely it should have been able to at least close its mouth more than halfway and be able to apply the necessary forces? Whitey and his colleagues modeled the mouthparts of Anomalocaris and the exoskeletons of trilobites and subjected them to various engineering analyses. Turns out that the story of these nektic predators grabbing and killing trilobites just can’t be true. Their mouths could exert significant sucking forces, though, so maybe they were predators on soft-bodied worms they pulled from the sediment. Their “teeth” then may have served mainly to keep the worms from sliding out once in the mouth. Not nearly so dramatic, but a much more sensible take on the fossil evidence.